Art of uniting glass and celluloid



Dec. 25, 192?. 1,478,862

' H, ROSENTHA L ART OF UNITING GLASS AND CELLULOID Filed Feb. '7, 1920E19 EW- @29 HW E y- [five/ital": flarfyifaaenikaz Patented Dec. 25,1923.

UNITED STATES HARRY ROSENTHAL, OF NEW YORK, N. Y.

ART OF UNITING GLASS AND CELLULOID.

Application filed February 7, 1920. Serial No. 356,878.

' To all whom it may concern.

Be it known that I, HARRY RosEN'rHAL, a citizen of the United States,residing at New York, in the'county of New York and State of New York,have invented certain new and useful Improvements in the Art of UnitingGlass and Celluloid, of which the following is a specification.

My invention relates to improvements in the art of uniting glass andcelluloid or its equivalent for any desired purpose.

The invention is particularly adapted for use in the manufacture ofsafety or nonscatterable glass wherein much difficulty has beenexperienced in producing in an economical manner and without danger ofbreak ing the glass a joint or union, between a sheet of celluloid and asheet of glass, of sufficient strength and durability to prevent theseparation of pieces or particles of glass from the celluloid should theglass be broken through accident or otherwise, and much difficulty hasalso been experienced in obtaining a product which is perfectlytransparent or optically clear.

The object of the invention is to overcome the said difficulties; andwith this and related objects in view, the invention consists in the artor process of forming a joint or union between the glass and thecelluloid, as will be hereinafter described and claimed.

In the accompanying drawings, illustrating the manner in which theinvention is carried into effect,

Figure l is an edge View of a sheet of glass.

Figure 2 is an edge view of a sheet of glass provided with a. gluecoating.

Figure 3 is an edge view of a sheet of celluloid.

Figure 4 is a view showing the sheet of celluloid applied to the gluecoating.

-Figure 5 is an edge view of a two ply product wherein a sheet of glassand the sheet of celluloid are united.

Figure 6 is an edge view of a three ply product wherein two sheets ofglass and an interposed sheet of celluloid are united.

In performing my improved art or process, I take a sheet of chemicallyclean glass, as shown at 2 in edge view in Fig. 1, and coat'it with asuitable glue, as shown at 3, in Fig. 2, in any suitable manner, andallow the glue coating 3 to dry.

-After the glue coating 3 has dried, I soften the exposed surfacethereof with a microscopical film of glue solvent, such as water,

which is not a solvent of celluloid, and which I spread upon saidsurface so thin that it will not penetrate the glue coating to theglass, thereby preserving the weld or union between the glue coating andthe glass. I then soften one surface of a sheet of celluloid, as shownat 4, in Fig. 3,. by any suitable means and place the softened surfaceof thecelluloid against the softened surface of the glue 3, press theglass 2 and celluloid 4 together by any suitable means, and permit theglue coating to dry.

To ensure a perfect union between the softened surface of the gluecoating and the celluloid, I soften the surface of the celluloid by theemployment with the glue sol- Vent of a liquid which is not a solventfor either the glue of the celluloid, but which is potentially capableunder the conditions of my improved art or process of bringing about anintimate commingling and interlocking of the molecules of the glue andthe celluloid at the surface of contact, resulting in a perfectly weldedunion and producing the desired result. Such a liquid is methylicdenatured alcohol, which is combined'with the glue solvent by forming asolution which is 90% alcohol and 10% water or gluesolvent I It is thefunction of the alcohol to'act as a vehicle for carrying the water whichhas a superficial softening action on the glue while the alcohol has asuperficial softening action on the celluloid, thus rendering the.

two substances capable of being welded together at their points ofcontact by the aid of pressure preferably combined with heat.

I shall now describe 'in detail a satisfactory method which I have foundto produce good results in carrying my invention into effect.

The sheet of glass 2 is thoroughly cleaned, dried and polished, by anyordinary means, and, subsequently, care is taken to prevent dirt fromgetting on to the surfaces, especially finger-marks or anything of agreasy nature. One surface of the sheet glass 15 then coated with a gluewhich" is preferably a solution of gelatine and formic acid, grams ofelatine to one. quart of form c acid, specifi c gravity 1.06. Thissolution is carefully spread over the surface by being sprayed or pouredthereon, preferably the latter.

After spreading the solution over the whole surface of the sheet ofglass it is tion of 90% and 10% water by volume. The said formula upon.it is face tension, is tipped off wi absorbent paper, and the sheet ofglass is brought back P to a horizontal position. It is then put into asuitable drier, and dried in stillair for about three hours at 210degrees to 220 de grees F. or for about fifteen hours at 150 degrees to160 degrees F. This renders the glue or gelatine bone dry, a conditionnecessary for making a perfect product. The sheet of glass is thenremoved from the drier and allowed to cool down to room temperature.This cooling may be hastened by placing the glass on a which quicklyconducts the heat therefrom.

The sheet of glass 2 with the dried glue coating 3 thereon is thendippedinto a solucompletely denatured alcohol, such as U. S. Governmentformula No. 1,

is: To every 100 parts by volume of ethyl alcohol of not less than 180degrees proof there shall be added 10 parts by volume of approved woodalcohol and one-half of one part by volume of approved benzine. Theglass is allowed to remain in the solution for a period of about threeseconds, whereremoved and drained from one corner until the solutionfails to run in a steady stream, but just begins to drop. The sheet ofglass is then put upon a clean flat surface, gelatine side up. The sheetof 'celluloid 4 cut the same size and shape as the glass 2 is dipped inthe same solution and drained in the same manner and placed upon thecoated glass plate already dip ed, care being taken to insure that its e'ges are in exact registry with the edges ofthe glass. The alcohol andwater solution is maintained at a temperature of degrees to degrees C.by suitable means such as hot water surrounding the tank containing -it.This is done to lessen the evaporation paper quality.

upon the series of papers a piece from the wet "surfaces because a rapidevaporation of alcohol leaves behind an excess of water. a

The assemblage-of glass and celluloid is now laid upon a piece oflinoleum about one-eighth of an inch thick and the same size as theassemblage, and a like piece of linoleum is put upon the top of theassemblage. On top of the upper piece of linoleum is put a series ofpapers, news- The first paper next to the linoleum is much smallerthanthe assemblage in area andis put upon the central portion thereof. Thesucceeding papers of the series increase in area by about onehalf inchincrements until the entire assemblage is covered. Finally, there is putof fine cork heavy iron plate or relatively softer linoleum the samesize as the glass and celluloid, and the assemblage thus completed isplaced in a suitable hydraulic press and a pressureof pounds to 250pounds per square inch is applied to the assemblage therein, the ressurebeing governed by the size, quality andv thickness of the glass. Theseries of papers as above described are included in the assemblageplaced in the press to insure that the first pressure will be applied tothe central portion thereof and that the pressure will then be graduallyextended to the edge portions thereof to force out the alcohol solutionand air bubbles as the pressure increases.

During the application of the pressure,-

the pressure plates of the press are malntained at a temperature ofabout '140 degrees F. by water circulating within them, or othersuitable means; and the pressure is maintained for a period of abouttwenty minutes, whereupon the pressure is released, the entireassemblage is removed from the press and the united glass and celluloidremoved from between the linoleum pads. The pressure temperature may bevaried from .that' set forth only within certain limits, because a muchlower temperature fails to remove the alcohol sufficiently, and a muchhigher temperature causes the celluloid to lose its resiliency.

composite Denatured alcohol, as herein set forth, is

not a solvent of gelatine or celluloid. alcohol acts primarily as acarrier for the water which has a softening action upon the gelatine andit acts secondarily as a softening agent for celluloid. Under thetemperature and pressure conditions of my improved art or processthereis a natural selection by the gelatine of the water of the solution, andby the celluloid of the alcohol of the solution to the end that there isa superficial softening of the two substances which permits anintermingling and interlocking of the molecules resulting in the desiredadhesion between the parts.

Poor adhesion is because the gelatineand celluloid are not softenedsufliciently to admit of a thorough interlocking of their molecules.

Pressure is necessary to bring about the interlocking of the moleculesnot only, but also to remove from between the glass and celluloid theair bubbles and the excessaleohol.

The relative proportions of alcohol and water in the solution thereofmay bevaried The likely to result if the pressure is applied at roomtemperature,

within limits to suit the requirements of different grades of celluloid.

The process hereinfore described for uniting a single sheet of glass anda single sheet celluloid is adaptable for uniting two sheets of glass toasheet of celluloid interposed between them, resulting in a three plyproduct, as shown in Fig. 6; and it is also adaptable for uniting anydesired number of sheets of glass having a sheet of celluloid interposedbetween each two adjacent sheets Y is normally less. soluble than theglue or gel- 1 atine, such, for example, as parafiine; and I accomplishthis by dipping each ed e of the two or more ply composite product orabout three seconds in parafline maintained ata temperature of about 200degrees. F. At this temperature and during this period of time,

enough heat is transmitted to expel from the edge traces of alcoholwhich mi ht not have been'eliminated by the heat and pressure in thehydraulic press. This treatment forms an edge seal which offers perfectresistance to water and any other liquid which this type of productwould be subjected to in ordinary practice. v

With the completion of the edge sealing, we have the finished product,reinforced glass ready to be cleaned and put in stock. While I havedescribed in detail herein the preferred method of carrying my inventioninto effect, I desire it to be understood that the same may be greatlymodified without departing from the actual scope of my invention.

I claim 1. The art of uniting glass and celluloid which consists incoating a surface of-a piece of glass with glue, permitting the gluecoating to dry, softening the exposed surface of the coating with a gluesolvent, softening a surface of a piece of celluloid by coating it witha liquid which is not a solvent for the glue or the celluloid but whichwill effect a softening of the latter, and pressing the softenedsurfaces of the glass and celluloid together by a pressure which isapplied first at the central portion of the parts and thereafterextended to the edge portions thereof.

2. The art of uniting glass and celluloid which consists in coating asurface of a piece cf glass with glue, permitting the Inc coating todry, softening the expose? surface of a coating with'a glue solvent,softening a surface of a piece of celluloid with alcohol, and pressingthe softened surfaces of the glass and celluloid together by a pressurewhich is applied first at the central portion of the parts andthereafter extended to the edge portions thereof.

3. The art of uniting glass and celluloid which consists in applyingglue to opposing faces of a piece of glass and a piece of celluloid,pressing the said faces and interposed glue together, and sealing theedges of the aiiggmbled parts by dipping them in hot para e.

4. The art (if uniting glass and celluloid which consists in coatingasurface ofa piece of glass with glue, permitting the ing to dry,softening the exposed surface of the coating with a glue solvent,softening a surface of a piece of-celluloidby coating it with a liquidwhich is not" a solvent for the glue or the celluloid but which willeffecta softening of the latter, pressing the softened surfaces of theglass and celluloid together, and sealing the edges of the assembledparts by dipping them in hot pal-affine. 1

5. The art of uniting glass and celluloid which consists i'ncoating asurface of apiece of glass with glue, permitting the glue coating todry, softening the exposed surface of the coating with aglue solvent,softening a surface of a piece of celluloid with alcohol, pressing thesoftened surfaces of the glass lue coatand celluloid together, andsealing the edges hereto.

' HARRY ROSENTHAL.

